1. Field of the Invention
The present invention relates to a flow path constituting member for an ink jet recording head, having a low stress and a chemical resistance and capable of forming a highly precise flow path by patterning for example by ultraviolet irradiation, an ink jet recording head including such flow path constituting member, and a method for producing an ink jet recording head.
2. Related Background Art
An ink jet recording head employed in an ink jet recording method (liquid discharge recording method) is generally provided with a plurality of constituting units, each including a small discharge port (also called orifice) for a recording liquid, a flow path communicating with the discharge port, and a liquid discharge energy generating unit provided in a part of the flow path. For obtaining an image of a high quality with such ink jet recording head, it is desirable that a small droplet of the recording liquid such as ink, to be discharged from the discharge port, is discharged from each discharge port always with a constant volume and a constant discharge speed. For achieving such state, Japanese Patent Applications Laid-open Nos. 4-10940 to 4-10942 disclose a method of applying a drive signal corresponding to recording information to an ink discharge pressure generating element (electrothermal converting element), thus causing the electrothermal converting element to generate thermal energy causing a rapid temperature increase in the ink to exceed a nucleus boiling thereof, thereby forming a bubble in the ink, and causing such bubble to communicate with the external atmosphere to discharge an ink droplet.
In an ink jet recording head realizing such method, a distance between the electrothermal converting element (heater) and the discharge port (orifice) is preferably as short as possible (such distance being hereinafter called xe2x80x9cOH distancexe2x80x9d. In the aforementioned method, since the discharge volume is substantially determined by the OH distance, it is essential that the OH distance can be exactly and reproducibly selected.
Therefore, for producing an ink jet recording head having a highly precise OH distance, Japanese Patent Application Laid-open No. 6-286149 discloses a producing method for an ink jet recording head including (1) a step of forming an ink flow path pattern with a soluble resin, on a substrate on which an ink discharge pressure generating element is formed, (2) a step of dissolving a coating resin, containing an epoxy resin which is solid at the normal temperature, in a solvent and solvent coating such coating resin on the soluble resin layer thereby forming a covering resin layer constituting an ink flow path wall on the soluble resin layer, (3) a step of forming an ink discharge port in the covering resin layer above the ink discharge pressure generating element, and (4) a step of dissolving out the soluble resin.
For the resin employed in the method of the aforementioned patent specification, there is being employed a cationic polymerized product of an alicyclic epoxy resin in order to form a pattern of a high aspect ratio and to obtain an ink resistance.
However, the use of the cationic polymerized product of the alicyclic epoxy resin leads to following drawbacks.
The cationic polymerized product of the alicyclic epoxy resin, though being excellent in the adhesion force, shows a peeling in case of a high internal stress, because of a high mechanical strength.
Such drawback tends to occur particularly in case the head is made longer or the resinous composition becomes thicker.
An object of the present invention is to provide a flow path constituting material for an ink jet recording head, having a low stress and a chemical resistance and capable of forming a coated film enabling easily pattern formation for example by an ultraviolet irradiation, an ink jet recording head utilizing such material, and a method for producing an ink jet recording head.
The flow path constituting material of the present invention for the ink jet recording head is featured by an epoxy resin composition including an epoxy resin containing two or more epoxy groups within a molecule and a unit represented by a following general formula (1), and a compound selected from a cationic polymerization initiator, an amine and an acid anhydride: 
wherein R1 represents xe2x80x94H or xe2x80x94CH3; R2 represents xe2x80x94CH2xe2x80x94, xe2x80x94(CH2)2xe2x80x94 or 
and R3 represents 
The ink jet recording head of the present invention is featured by including a flow path constituting member for the ink jet recording head of the above-mentioned configuration and a substrate on which an ink discharge pressure generating element is formed.
The method of the present invention for producing the ink jet recording head is featured by including (1) a step of forming an ink flow path pattern with a soluble resin, on a substrate on which an ink discharge pressure generating element is formed, (2) a step of dissolving a covering resin, formed by an epoxy resin composition including an epoxy resin containing two or more epoxy groups and a unit represented by a following general formula within a molecule, and a compound selected from a cationic polymerization initiator, an amine and an acid anhydride, in a solvent and solvent coating such covering resin on the soluble resin layer thereby forming a covering resin layer constituting an ink flow path wall on the soluble resin layer, (3) a step of forming an ink discharge port in the covering resin layer above the ink discharge pressure generating element, and (4) a step of dissolving out the soluble resin: 
wherein R1 represents xe2x80x94H or xe2x80x94CH3; R2 represents xe2x80x94CH2xe2x80x94, xe2x80x94(CH2)2xe2x80x94 or: 
and R3 represents: 
The use of such epoxy resin composition allows to obtain a covering resin layer capable of forming a flow path without surface irregularities which can cause ink trapping, and also to achieve a low stress and a chemical resistance, thereby enabling to produce an ink jet recording head improved in production yield and quality, with a significant decrease in drawbacks such as peeling.